bh85

I have 2010 KHS CX-200. Its a nice CX bike from back in the day. Its my gravel bike, among the others. It comes with Tiagra 9 speed shifters and Tiagra front derailleur. Crankset is 9 speed FSA 46/36. Rear derailleur is 105 SS 4600. Shimano says max cog is 27t. Casette on it is 12-25. I would like to get some better gear range for climbing. What would be the cheapest option to go with. I was thinking about maybe going with Alivio M3100 9 speed and 11-36 cassette. I think it would work with 9 speed Tiagra shifters? Another option would be to replace it with new groupset, in which case I might go with Sensah SRX 1x11 with 42t crankset and 11-46 cassette. Not sure which way to go. Any help is appreciated from gurus.

SurferRosa

So you want "lower" gears (maybe with larger rear cogs), the opposite of "bigger gear ratio."

bh85

Yes, sorry brain wasnt working. Need some lower gears in the back. My lowest now is 25t.

alcjphil

OK, so all you need is any Shimano compatible "9 speed" mountain bike derailleur that can handle the sort of cassette you want to buy. Oh, and the cassette and chain of course. Shimano and Microshift both still make derailleurs that will fill your needs

bh85

Do you think Alivio M3100 9 speed would work? It’s the newest Alivio RD that can handle 36t. Not sure if anything changed with new ones.

Hondo6

Sheesh - having a stranglehold on the PC software market wasn't enough for Bill Gates? He had to branch out into making bike components too?

Just kidding, alcjphil. We know you meant MicroShift.

hokiefyd 

It will, but I've found the Shadow style derailers like these, which don't pivot the upper pulley wheel up with cage rotation, to have sluggish shifting across the smaller sprockets of the cassette, because the chain's further away from meshing tightly with those sprockets.

Instead, I'd recommend a Deore RD-M591. It's one of the last traditional style Deore rear derailer and it's a pretty stout piece. Shimano says it will support up to 34T, but I can say from personal experience that it'll handle at least 36T.

Another option is the Alivio series RD-T4000. It's one step down from Deore in Shimano's line up and is a current production derailer. Like with the M591, it supports up to a 34T, but I run this derailer with a 40T on one of my bikes and it clears it with ease.

Lombard

This is the route I would take. Deore is the workhorse of mountain bike drivetrain parts.

And yes, Shimano's limits are conservative and can usually be safely exceeded by 2 teeth. I have GS road derailleurs with limit ratings of 32T. I run 34T cassettes with no problems. Just be sure to test it in the stand first and make sure you don't bind the gears when going into the large-large combo.

bh85

You run t4000 with 40t? Is it 2x or 1x? What chainrings are you running?

alcjphil

That darned autocorrect. Fixed it

hokiefyd 

It's on a fat bike right now with a 22-32-42 3x and a 12-36 cassette. It runs all combinations of that drivetrain well. I was using it in a 1x configuation (36t) with the 11-40 cassette.

It should be pretty easy to make work with a 1x. The T4000's cage is really long...in this case, I'd size the chain so that it pulls the cage forward just enough to clear the 40t sprocket...that should be it. It may be more difficult to make work with a 40t and a 2x/3x setup.

It looks like you were considering it with an 11-36 cassette and 2x...it should support that pretty well.

wrobertdavis

Have you considered attacking this from the crankset instead? You might possibly be able to change rings to 24-38 and get an improvement in the climbing without much cost or hassle.
You would give up 3-4 mph on the top end but that should not be an issue for gravel or mountain riding.

bh85

I did think about switching whole crankset to something like 46-30. Right now I have 46-36. But even with that, my RD is limited to 27t, per shimano. I would like 1:1 ratio at least. So, 30-30, or 36-36.

bh85

So I ended up going with Alivio M3100 Shadow, and 11-36 casette with 46-36 crankset. Alivio is shifting smooth and works great with my set up. Originally, my 2010 KHS CX-200 came with Tiagra 2x9 with 105 SS rear derailleur, which was limited to max 27t but came with 11-25 casette, and 46-36 CX crankset. Might get a different crankset like 46-30 to get me even better low gear. But happy that I gained 11 extra teeth on the rear derailleur.

Andrew R Stewart 

Back when indexing was just becoming "the way" I use to describe component interchangeability this way. "Everything MicroSoft knows about planned obsolescence and compatibilities was learned from Shimano". Not true of course but no one misunderstood my opinion and most agreed Andy